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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            /* 6隐藏子盒子 */
            overflow: hidden;
            /* 1盒子 */
            width: 200px;
            height: 200px;
            border: 1px solid pink;
            margin: 10px;
            /* 7 多个旋转案例浮动起来 */
            float: left;
            }
            div::before {
                /* 2伪元素属于行 给宽高选转换 */
                display: block;
                content: "黑马";
                width: 100%;
                height: 100%;
                background-color: hotpink;
                /* 3以左下角为中心旋转90deg */
                transform: rotate(90deg);
                transform-origin: left bottom;
                /* 5添加过渡效果更完美 */
                transition:all .4s;
            }
            /* 4鼠标经过div 里面的before 复原 */
            div:hover::before {
                transform: rotate(0deg);
            }
    </style>
</head>
<body>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
   
</body>
</html>